Question:  Can you tune it to 28hz ?
Answer: Yes.  Tuning lower than mfg recommendations is an option.  When tuning lower than recommended, port area has to be adjusted accordingly to or else it will only play that frequency.   It will still lose some bandwidth and high end extension. The output on that lower frequency is drastically increased which is the goal for most who want an enclosure tuned lower than normal.  

Question:  Can you design a box for 2 12s under my seat?
Answer: No.  Bigger subs is not always better especially when space is limited.  If you were to cram 2 12s in the enclosure, a single high end 8 will outperform them in the same size box.  A single high end 6.5 sub in an 8th order bandpass will do over 140db at 40hz. in a box big enough for a single 12.

Question:  Do you guys build and ship custom enclosures?
Answer:  Yes, but on a very limited first come first serve basis.  To save on shipping, it is better to have a friend who is handy with tools build your enclosure if building it yourself is not an option.  The enclosures we build are generally very complicated, time consuming high end builds with LEDs, acrylic, and reflective stain finish on Baltic birch.

Question:  What software do you use to design enclosures?
Answer:  Sketchup 3-D modeling software, Mobile Info Labs port calculator, and over 20 years of real world car audio experience is the magic behind our designs.

Question:  What software do you use to simulate responses?
Answer:  Except for testing new ideas or rare one-off designs, we do not use response simulator software.  In order for sims software to work correctly, you have to have the correct T/S parameters for your subwoofer.  The parameters on some mfg websites are not accurate and most are incomplete.  Some enclosures are tuned for a specific cabin space of small or large vehicles that sims can not factor in.  There is nothing better than the real world experience of what works and what doesn't.  
Question:  How long does it take to get my design after I place my order?
Answer:  Before you place your order, you will see "current lead time" at checkout.  In most cases, designs are delivered within 1-2 business days.